21213567 has 12 divisors (see below), whose sum is σ = 31974384. Its totient is φ = 13527360.

The previous prime is 21213559. The next prime is 21213583. The reversal of 21213567 is 76531212.

It is a happy number.

It is not a de Polignac number, because 21213567 - 2³ = 21213559 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21213567.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213667) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 51034 + ... + 51447.

It is an arithmetic number, because the mean of its divisors is an integer number (2664532).

Almost surely, 2^21213567 is an apocalyptic number.

21213567 is a deficient number, since it is larger than the sum of its proper divisors (10760817).

21213567 is a wasteful number, since it uses less digits than its factorization.

21213567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102510 (or 102507 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21213567 is about 4605.8188197106. The cubic root of 21213567 is about 276.8245270945.

Adding to 21213567 its reverse (76531212), we get a palindrome (97744779).

The spelling of 21213567 in words is "twenty-one million, two hundred thirteen thousand, five hundred sixty-seven".